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GATE 2025 BM – Question 11

Analog and Digital Electronics · Semiconductor Devices · 1 mark · Multiple choice

Two 1 cm³ cuboids are made of gold and undoped silicon. What happens to their resistivities as temperature rises from 300 K to 350 K?

  1. Gold increases; undoped silicon decreases
  2. Gold decreases; undoped silicon increases
  3. Gold unchanged; undoped silicon increases
  4. Gold decreases; undoped silicon unchanged

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Correct answer: (A) Gold increases; undoped silicon decreases

Explanation

In a metal such as gold, increased thermal lattice scattering reduces electron mobility, raising resistivity. In intrinsic silicon, heating creates many more electron–hole carriers, and the carrier-density increase dominates, lowering resistivity. Thus A; equal block volume is irrelevant to resistivity, an intrinsic property.

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